Control system and to the control of fluid operated mechanism



June 25, 1935. M A 2,005,867

' CONTROL SYSTEM AND TO THE CONTROL OFTFLUID OPERATED MECHANISM Filed Jan. 24, 1934 v 5 Sheets-Sheet 1 .772 ven f0 1' June 25, 1935. M. MAAG CONTROL SYSTEM AND TO THE CONTROL OF FLUID OPERATED MECHANISM Filed Jan. 24, 1934 3 Sheets-Sheet 2 5a I a \I 7 8 5 l g6 Jnvenfar' June 25, 1935. M. AAG 2,005,867

CONTROL SYSTEM AND TO THE CONTROL OF FLUID OPERATED MECHANISM Filed Jan. 24, 1934 3 Sheets-Sheet 5 ,3 5 Q 520 \540 I 1' I 5 A Patented June 25, 1935 CONTROL SYSTEM AND TO THECONTROL OF FLUID OPERATED MECHANISM Max Maag, Schwamendingen, near Zurich,-

' Switzerland Application January 24, 1934, SerialNo. 708,136

In Germany January 23, 1933 8 Claims. (01. 34-336) This invention relates to a control system and to the control of fluid-operated mechanism, more particularly tothe pneumatic control of organs or other wind-operated musical instruments. The object of my invention is the provision of improved means for regulating pneumatic pressure and/or the rate of the increase and decrease of pneumatic pressure in pneumatically operated mechanism, particularly in organs.

Ishall describe my invention hereinafter with reference to its'application to the wind control of an'organj but-I wish it to beunderstood that my 'in'vention is broadly applicable to any fluidpre'ssure control. Other'objects of my invention will appear from the description following hereinalter and "the features of novelty will be pointed out in the claims.

7 A 'preferred embodiment of my invention is illustrated inthe drawings in which Fig. 1 is an axialsection of a simple form of my ,improv'ed valve mounted in adivision stop chest (Registerkanzellenlade) Fig. 2 shows a detail of this valve structure;

Fig. 3 is" an axial section of a modified'valve mounted :in an undivided chest' (k'anzellen-losen Lade) having separateblowingor operating chambers;

Fig. 4 is an elevation of the valve-unit viewed from the left of Fig. 3;

Fig: 5 is anaxlal section of amodified valveunit mounted in a box? chest;

Fig.. 6 is the section F .5;

taken along line 6-6 of Fig- 7 is an elevation of thevalve-unitviewed from the left of Fig. 5;"

Fig. 8 is the section taken along line 8.& of Fig.

'7 on an enlarged scale;

Fig. 9 is a sectional diagrammatic illustration of an instrument provided with a plurality of tone-producers and equipped with my improved controlling system.

" the arrangement being sure prevailing in the operating wind.

such that the wind preswind chest produces the produced and maintained in the controlling Withreierence to Fig. 9; three tone producers 5t, 52,- 53 are mounted on a common wind chest 54 and communicate individually andsepai'ate'ly with three Wind chambers 55, 56, 51 whicl'rare connected with a common Wind way" 54? through i ports each of which is controlled by a floating valve 58, 59 and 80. On'the other side of the wind-way opposite to the windchambers; there are provided control chambers 6 I; Brand which are sealed from the wind way by re'silient-diavphragms or bellows, 65, 66-. Each bellows-"is connected with the coordinated valve flap-for common movement by a rodB-l, 68 'or- 69 respectively. The control chambers are supplied with compressed air or wind from'acommon relay 3 wind chamber through conduits 'll,- 12--and-13 which are individually and separately controlled by key-actuatedvalves diagrammatically indicated at T. If desired, the control chambers H, 82, 63 may be supplied with-wind from'the-wind way and, in this event,- the conduits- H,- 125 I3 terminate in saidwind way. The valve 5l-or 59 or 8!! respectively which is arranged-to-open'into the operating chamberof the tone-produceris of the floating type, that is to say, it will float, when operated, in an intermediate position in which the opposed pressures of the operating wind-acting onthe valve flap and of the relay wind acting on the diaphragm connected to the mp balance each other. I It is an object of my invention to provide a con: trolling system permitting such valves to be used inorgans or other musical wind-operated-instruments in which the different tone-producers require a different operatingpressure. As this operating pressure depends on the pressure prevailing in the controlling chamber, as will beex'plalned hereinafter, it is a requirementthat, when a key is actuated, a predeterminedpressur should be chamber. I attain this object by individually c'oordinating separate controllingchambrs to the different floating valves, eachof saict' chambers being provided with an inlet'and anoutlet port.

The pneumatic pressure built-upin'th'ecorrtrolling chamber'upon key actuation depends-"on the dimensions of said ports and, hence, the ports may be so dimensioned thatth'e op era-tlng pr'ssure for each tone-producer will have" the desired value. In order to" facilitate the job'of intonating the tone producers and in orderto provide for a possibility of exclranging-= the toneproducers and of conveniently tuning the same, I prefer the provision of adjusting means"'whereby the two independent inlet and outlet ports" of with A; the atmospheric pressure with b; the

the control chamber may be varied and their cross-section may be chosen in dependence on the wind pressure required for operating the coordinated tone-producer in each particular case.

As the response of the various tone-producers depends not only on the operating wind pressure, but also on the speed of increase and decrease of this presure,.I prefer to dimension the inlet and outlet'ports of the control chamber in such a manner that the pressure increase upon a key depression and the pressure decrease upon a key release will have the rate required for a proper response of the coordinated tone-producer and for a proper decay of the tone. With a given crosssection of the inlet and outlet ports, the same object, that is to say, the control of the rate at which the operating pressure increases and decreases, may also be attained by suitably dimensioning the volume of the control wind chamber.

With reference to Fig. 9 it will be noted that the inlet conduits H, 12 and 13 of the control chambers 8|, 62 and 83 which are separately coordinated to the tone-producers 52 and 53 are each provided with adjusting means in the form of a regulating cook 14, I5 or I6. Similarly, each control chamber is provided with a separate outlet conduit 11, or 18, or 19 respectively, and this outlet conduit is regulatable by an adjustable cock 80, or 8|, or 82 respectively.

Hereinafter, I shall analyze the pressure conditions controlling the operation of the first toneproducer, it being understood that the same conditions apply equally to the other tone-producers and control valves.

The supply wind pressure prevailing in the wind chest may be designated by p, the pressure in the relay wind chamber 1): (as above stated, these two pressures may have the same degree), the pressure in'the control chamber 91, and the pressure become larger than the difference of the pressures p and p5 acting on the diaphragm 64 from opposite sides. Consequently, the valve flap 58 will be slightly lifted and will permit compressed air from channel- 54' to enter the operating chamber 55, thus raising the pressure in the operating chamber to 132, this being the operating pressure blowing the tone-producer 5|. The pressure 1):, however, acts also on the valve flap 58 from above and causes the valve flap to float in a. position in which it is .keptin equilibrium by the different forces tending to open and close it.

I shall hereinafter designate the free crosssection of the air admission port 14 with E; the

super-pressure of the relay wind in chamber over the atmopsheric pressure with pr and the super-pressure in the control chamber over the atmospheric pressure with n. The computing problem isto express in as a function of the other data.

equal to the amount discharged through cock 14, it will be apparent that that is to say, the pressure 91 in chamber 6| depends entirely on the ratio of the cross-sections provided that the wind pressure pr is given.

It follows, that the degree of the controlling pressure may be chosen, as desired, in accordance with the requisite operating conditions of each individual tone-producer by arbitrarily terminating the ratio that is to say, by suitably dimensioning the relative cross-sections of the inlet and outlet ports of the respective control chamber. The operating pressure 102 equals substantially the controlling pressure pi as will be understood from the following consideration: As soon as compressed air is admitted below the diaphragm 54, the above explained equilibrium existing between the supply wind pressure acting on the valve flap 58 and on the diphragm 64 will be disturbed whereby the diaphragm 64 and the valve flap 58 are lifted. As soon as the valve 58 opens, compressed air enters the chamber 55 from the channel 54 and raises the pressure in chamber 55 to m, p: beins the requisite pressure for operating the toneproducers. m of course tends to close valve 58 and the degree of m follows from a consideration of the conditions of equilibrium of the floating valve. These conditions may be expressed by the following equation:

+Dp+mm=0,

it being assumed that the effective surfaces of the valve flap 58 and of the diaphragm 64 are substantially equal. The equation proves that m equals 111, that is to say, the pressure in the operating chamber in is always substantially equal to the pressure 111 prevailing in the control chamber. Consequently, the operating pressure in also depends on the ratio As above mentioned, it is an object of the invention to provide means for arbitrarily determining or regulating the rate at which the operating pressure increases to its full value upon the key actuation and the rate at which it decreases upon the release of the key. For this purpose I have provided means permitting to effect such a control for each tone-producer separately and to thus satisfy the individual requirements of the different instruments. These means comprise mechanism for varying the cross-sections of the inlets and outlets of the control chambers. Such mechanism may be in form of exchangeable throttling elements but is prefer- :ably formed? by adjustable throttle .valve I such as iindicatediinzl lig. 9; at 514,215, I6, 80,i8I.-and;82.

lhe operatingzpressure in the base-of the dif- :ferent instmmentssuch as .pipes, varies conadverselyafiecting the-response and the sound :of the instrument. The response may be imaprovedby providing alarge entranceport at the ifootybut .this'requires that the: difference in pressureibetween the base: and the operating cham- Lber-becomparatively small. Prior to my inven- 'rtioniitwas-customary,:for thispurpose, to insert iregulatingibellows between the source of pressure andtthe wind chest for reducing the pressure to ithe-required degree. It will be readily appreci- .ated thatthe-necessity of providing a large numfiber of such regulating bellows increases considerably the cost of manufacture,-quite apart from :the 'fact that the bellows require'considera'ole space.

It is an object of my invention to do away with Ltheseregulating bellows altogether, and I attain this object by the improved valve system which permits arbitrarily determining the wind pressure in the control-chamber by asimple adjustment, irrespective of the wind pressure and of .the cross-section of the foot port of the pipe. Another advantage-oilered by my invention is thepossibility of'easily-regulating the sound vol- :ume of the tone-producers independently, as .above explained. This 'facilitates the tuning operation considerably. Prior to my invention thistuning-operation required a change of the baseinletports of the pipes and normally this -change required a disassembly of the pipe. With my inventionthe foot port of thepipe may be made as large as desiredfrom the beginning and itwill not-be-necessary to disassemble the pipe for regulating its-sound volume, as the control -wind pressure needs only to be varied by suitable adjustmentof the throttling means controlling '"The arrangement and-function of my improved valve system will be 'easily understood from a -description-of Fig. 1. The wind pressure 1) prevailing in the wind way I of the wind chest acts 'on a diaphragm 2"WhlCh is attached to a ring 3 inserted in acasing 4 which is mounted and suit- =ably sealed within an opening provided in the bottom wall-5 ofthe'wind way. The air pressure p in the spaceI acts also on a valve plate 8 which -is connected with the diaphragm 2 by a pull member I. The valve plate 8 is adapted to seal the-upper end of atubeillinserted and sealed within a suitable opening in'the top wall 9 of the chest.

The'diaphr-agmi 'and the valve plate'8 are so dimensioned that'the'total pressure acting on "thediaphr-agm is a little larger than that acting ioni'the lvalveplate, whereby the valve is normally I :kept. in. closed position: in which-it interrupts the iohaambert I of the tone-producer I 2.

iIOWIJihBL diaphragm 2 'iand 'has an inlet port communicating with:an;aclmission;conduit ill .andan outlet port communicating xWith a discharge. con- 111111715. A cock :16 ilS inserted inithe admission .conduit I .4, and, similarly, :the discharge-conduit [5 maybe .moreorless throttleid .bya cock .I'I. The admission conduit 14 communicatesbypipe I8 with a suitable pneumatic or .electropneumaticrelays (not. shown) :whichisoperative upon depression-of anassooiatedkey to. supply conduit I4 with windof'thepressure pr. Thiswind en- 'ters the -.control chamber .below the diaphragm and .partly relieves the latter from-the iclosin pressure exerted by .p, dependingon.theidegree of pr. This .hasthe efiect that the pressure p tending to openthevalveplate willbecomeflarger.

than thedifierence .in the pressures p and pr .actingon the diaphragmand tending toclose the valve. opened permitting wind fromspace I to enter .the operating chamber II in whichthepressure willbe: raised to 192.

Therefore, the valve plate :8 will the The wind with the :pressure in operates the toneeproducer I 2 ,1 but. at. the same time tends to closethe valve plateaa keeping the latter in floating condition .in whichthe forces acting on the members 12 and :B ibalance each other.

As above explained, there. exists a definite proportion between-the pressure 101 .prevailingin the control chamber I3.and thepressure pzprevailing in the operating chamber I I,-these twoipressures being substantially alikezif the surfaces .of

the floating valve and. of the diaphragm-are alike.

With my improved control-system I may so-reguiate the pressure 101 in the control chamber lI3 regardless of the degree of the supply-pressure a pr that the operating wind pressure pa in the chamber II will have the degreerequiredin. the particular case for a proper operation of thetoneproducer-I 2. Assuming that the supplypressure pr be constant, it follows from the above explanations of the conditions prevailing that thecontrol pressure '231 in chamber I3 depends on the ratio of the areas of theinlet and outletrport,

the cross-section A of the outlet port being adjustable by cockll and the cross-section E of the inletport being adjustable by 000K915.

With cock Iii-being closed, that'is to say, with E=0, it will be understood that 121:0; with cock Iii-being opened and cockI'I being closed, that is amount of 102 will be smaller than pr or p; but this is of little importance if thepressure pzmay be increased by raisingthe pressure p1 withinthe possible limits to the maximum degree'req-uired for operating the different tone-producers mounted on the wind chest.

While the degree of the blowing pressure of the organ-pipe determines the proper volume and character of the sound, the rate atwhich this pressure rises upon key-depressionfrom 'zero to its" full amountor the rate at which the pressurewfi drops to zero upon the release of the key is of controlling importance for a proper response of the pipe and for a proper decay of its sound. If the pressure rises too fast, turbulent air-currents will be formed within the labium and will interfere with the proper formation of thestationary acoustic wave within the pipe and will produce a retarded improper response coupled with blowing sounds and upper harmonics, with too rapid a pressure drop, however, the decay of the sound is toosudden and abrupt. Too slow a pressure increase and too slow a pressure drop, however, re-

. suit in the well-known drawling of the tone which is due to the dependency of the tone of pipes on the operating pressure. A clear and smooth and yet faster response than obtainable with an unduly increased wind-pressure and a smooth decay is obtainable for each kind of pipe only by suitably regulating, within narrow limits, the speed of increase and decrease of the operating pressure, the pressure being sufiiciently low to avoid turbulent currents and yet high enough to obtain a tone which is no longer perceived by the auditor as a drawling tone, but appears to him .to be of agreeable softness.

My improved means for adjusting the operating pressure are also adapted to control the rate of decrease and increase of the blowing pressure. It will be appreciated that the rate of increase and decrease of the pressures p1 and thus of the pressure n may be varied by faster or slower charging or discharging the control chamber I3. This effect may be attained by increasing. or decreasing the cross-section of the cocks l6 and I1. The peculiar fact that the above described control of pressure degree does not depend on the absolute amount of the port cross-sections but on the ratio of the same only, permits with any given adjustment of the cock 16, to make the throttling cross-section of the cock I'l so small in any case as required for obtaining the desired ratio resulting in the pressure pi. Hence, it is aways possible to adjust the cocks l6 and I] so as to determine not only the desired degree of pressure n, but also the desired rate of increase and decrease of this pressure, provided the cockcross-sections be made sufficiently small. As the cock I1 is normally always more or less open, part of the air entering through cock l6 will be immediately discharged through cock I]. With the cock l'l being open, it takes a longer period of time for attaining the final condition than with the cock being closed. For attaining a. desired filling period, the cross-section of the cock l6 may be made relatively large so that it is less liable to get clogged by entering dust particles than if the cock H were closed or were absent altogether, in which event pr would equal 121, of course. Obviously, the rate of increase and decrease of the pressure may be arbitrarily determined with a given adjustment of the cocks by suitably dimensioning the volume of chamber 13, an increase of volume resulting in a reduction of said rate. This is illustrated in Fig. 9 where I have shown three different tone producers associated with control chambers 6|, 62 and 63 of diiierent volumes, chosen in dependence of the various characteristics of the tone producers.

Experience has shown, however, that in favor of a small air consumption this chamber may be made very small, provided the cock throttle cross-sections are well adjustable in their lower range. To this end, I prefer to employ cocks having ports of triangular cross-section as indicated inFig. 2. With such a cock, 9. very small cross-section only is opened by the initial opening adjustment of the valve, this cross-section being formed by the cooperation of a comer of the triangle with the circular ports l4 and 15.

The embodiment of my invention illustrated in wind is directly supplied from the chamber 3l3 10 which, in this particular case, is not a division stop chamber, but is a wind-chest which is common to all tone producers mounted on the chest and serves also to supply the blowing wind to the tone producers.

The diaphragm casing 304 is integral with a basket 3l0 carrying the valve-seat member. The whole valve structure constitutes a unit which may be easily inserted and removed from the chest, and may be assembled separately per se. Moreover, the rigid connection of the valve seat and the diaphragm casing offers the advantage that the distance of the diaphragm 302 from the valve seat 308 will not be affected by relative displacement of the bottom plate 305 and the cover plate 309 which are made of wood and, therefore, are liable to shrink or warp. To permit of such relative displacement, the head portion forming the valve seat is made cylindrical and is surrounded by a resilient layer 321 which compensates for a change of the shape of the opening accommodating the head portion of the casing.

The conduit 3l4 which supplies the controlchamber with the wind does not lead to a separate source of compressed air as in Fig. l, but leads to the compartment 3l9. Normally, the mouth of the conduit M4 is kept closed by a plate 320 of magnetic material, for instance of steel, which is guided by suitable means (not shown) to be movable in vertical direction only. A bracket 32I which is preferably integral with the diaphragm casing 304 supports an electromagnet 322 arranged above the plate 320 and operative, when energized, to lift this plate. The coil of the electro-magnet may be energized through wires 323 and 324 (Fig. 4) leading to terminal screws 325 and 326. The terminals are connected with leads 323a and 324a which are connected with the key-contacts through the intermediary of the customary register mechanism. When the electromagnet 322 is energized, it will lift the armature plate 320 and will thus open the conduit 3, whereby control-wind is admitted from the wind-way 3I9 to the controlchamber 3l3. This causes the valve plate 300 connected with the diaphragm 302 by rod 301 to be lifted, whereby wind is admitted from the compartment 3l9 through the openings of the basket 3l0 to the operating chamber 3 which is individually coordinated to the tone producer 3l2. The pressure of the operating wind depends on the adjustment of cocks 3I6 and 311, the cock 3H5 controlling the admission conduit 314 and the cock 3H controlling a discharge conduit 3l5.

The casing 304 is formed with a flange 328 which is detachably secured in place on the botton plate 305 of the chest by meansof screws, 32 9, a resilient washer 330 being interposed to secure a leak-proof connection. The diaphragm 302 is held in place in the casing 304 by a clamping ring 303 secured to the casing by suitable means not shown.

It will be noted that the valve unit illustrated in Figs.-3 and 4 is designed for insertion-in the chest, andfor adjustment, from below. Thereforepit is applicable'tosuch-chests only which are accessible from below.

In Figs. "5 to8,'I have illustrated a modified valve-structure whichmay beinserted in the top of the 'chcst and may be adjusted from above. This type of valve, therefore, may be used in case -the chest is not accessible from below.

The valve-unit comprises a diaphragm casing 504 iwhichis formed with a flange 53! bearing on"=the top 532 50f the chest, a washer 534 being suitablyinterposed to secure a tight seal. The diaphragm 'casing504 accommodates the valve seat member 5| fl-formed with a flange 535 bearing againsti the diaphragm casing flange 535, a washer! being interposed. The 'valve seat member 5|0 extends downwardly towards the bottom of the diaphragm casing 504 and bears wagainstzthe margin of the diaphragm 532, thus securing .and clamping "the same in position. The required clamping pressure is exerted by bolts .531 (Fig. 6 and 7) which extend through the :flange 535, through 'the wall of casing 504 andithrougha bottom-plate 538 so as to secure the various elements *of the unit to each other.

'The'wallsrof the casing 504 and of the lower portion of :the valve seat member are provided with large openings539 to'permit the wind in the chest to freelyenter'the space between the diaphragm 502 and the valve plate 508. An electromagn'et "522 of the shape shown in Fig. 6 is-inserted through one of these openings, the free ends of the core of the electromagnet being :inserted iniborings provided in the wall of the casing 504 at a level just above the upper mouth of a channel 514.

The mouth of this channel is normally closed by an armature plate 520 of magnetic material which is formed with a vertical pin 54! guided in an axial boring of a bolt 540 which is screwed from above into a tapped vertical boring provided in the wall of the casing 504 and passing between the two borings accommodating the armature core. Wires 523 and 524 lead from the coil of the electromagnet to terminal screws 525 and 526 which are inserted in, and suitably insulated from, the wall of the diaphragm casing 504. The terminal ends of the screws 525 and 526 are connected to leads 523a and 524a leading to the keyboard. The electromagnetic actuation of the valve plate 520 permits adjustment of the stroke of the valve and this adjustment may be effected by turning the screw 540 by aid of a handle 542 or similar means, such as a screw driver or a wrench. The stroke of the plate 520 is limited by the spacing of its upper face from the lower end of screw 540 and the length of this stroke determines the throttling cross-section of the conduit 514 which admits the control wind below the diaphragm.

It will be understood that this throttling crosssection may be varied by lowering or lifting the adjusting screw 540 and, therefore, this screw performs a similar function, as the cock 3H5 in the embodiment shown in Figs. 3 and 4. The conduit 5|4 provided for within the wall of the casing 504 communicates with a groove 543 in the plate 538, and this groove establishes the connection of the conduit 5 l 4 with the control chamber 5l3' below the diaphragm. A similar groove 544 connects the control-chamber with a vertical discharge channel 515 in the wall of the diaphragm casing 504, the effective cross-section of the discharge conduit being adjustable by a cock of an exhaust channel 548 providedfor in the' upper portion of casing 504.

A conical block 549 insorted in'thevalveseatmember 5K; confines with the latterthe operating chamber 5H and forms the support of "the tone producer 5512.

Although the three embodiments of my im proved valve structurehereinbefore described are adapted. for different purposes and, therefore,

differ from each other in construction, it will be appreciated that it is a characteristic of all ofthe different designs that the controlling chamber of a floating valve of thetype disclosed'in my U. S. Patent No. 1,681,547 is provided with two independent ports forthe admission and for the discharge of the controlling wind, means being provided to control the eifective cross-section of these ports, whereby the pressure of the blowing wind and the rate of increase and decreaseof this pressure may be independently adjusted so" as to satisfy the requirements ineach particular case.

' My invention is capable of numerous modifications within the scope of the appended :claims.

Under certain circumstances, it may suflice to adjust one of the twoports only, and the meansfor adjustment may comprise means other than cocks or the like.

What I claim is:

.1. Controlling system of the character de-' scribed comprising a plurality of pneumatically operable instruments of different characteristics, floating valves individually associated with and arranged to open towards said instruments to control the operation of the same, a separate control chamber for each floating valve, and means responsive to the penumatic pressure in each control chamber and connected with the associated floating valve whereby the amount of said pressure will determine the lift of and the throttling effect exerted by said floating valve, each control chamber being provided with an admission port and with a discharge port, the various ports being differentially proportioned and dimensioned in dependence of said characteristics.

2. Controlling system of the character described comprising a plurality of pneumatically operable instruments of different characteristics, floating valves individually associated with and arranged to open towards said instruments to control the operation of the same, a separate control chamber for each floating valve, and means responsive to the penumatic pressure in each control chamber and connected with the associated floating valve whereby the amount of said pressure will determine the lift of and the throttling effect exerted by said floating valve, each control chamber being provided with an admission port and with a discharge port, and means for adjusting at least certain of said ports in dependence of said characteristics.

3. In a controlling system of the character described, the combination of a pneumatically operable instrument with a control valve, a pneumatic relay including a diaphragm control chamher for governing said valve, a source of pressure, key-controlled mechanism for connecting said source with said chamber, and adjustable means adapted to variably determine the maximum pneumatic pressure in said chamber and the rate 545, compare Fig. 8. The cock member -hasan at which said pressure changes in response to the key operation of said mechanism.

4. Controlling system of the character described comprising a plurality of pneumatically operable instruments of diflerent characteristics, floating valves individually associated with and arranged to open towards said instruments to control the operation of the same, a separate control chamber for each floating valve, and means responsive to the pneumatic pressure in each control chamber and connected with the associated floating valve whereby the amount of said pressure will determine the lift of and the throttling effect exerted by said floating valve, each control chamber being provided with an admission port and with a discharge port, and cooks for adjusting at least certain of said ports in dependence of said characteristics.

5. The combination comprising a pneumatically operable instrument, a floating valve con trolling the same, a penumatic relay governing said valve and including a diaphragm chamber, said chamber being provided with an admission port and a discharge port and a cock for adjusting at least one of said ports, said cock being provided with a triangular passage, a corner of said passage cooperating with said port whereby the same may be gradually opened and minutely adjusted.

6. The combination comprising a pneumatically operable instrument, a floating valve arranged to open towards and control the same, a pneumatic relay governing said valve and including a diaphragm chamber, whereby the amount of pressure in said chamber will determine the lift of and the throttling effect exerted-by said floating valve, said chamber being provided with an admission port and a discharge port, an armature plate normally closing said admission port, a keycontrolled electro-magnet adapted to lift said plate, whereby said admission port will be opened.

and an adjustable stop for limiting the stroke 0! said valve.

'7. In an organ the combination with a pipe of a controlling unit comprising a floating valvearranged to open towards said pipe and a diaphragm connected to said valve, both being mounted within a casing removably inserted in the wind chest of the organ, a control chamber confined in said casing by said diaphragm whereby the amount of pressure in said chamber will determine the lift of and the throttling eflect exerted by said floating valve, said chamber being provided with an admission port and a discharge port and members mounted in said casing for adjusting the cross-section of said ports.

8. The combination comprising a pneumatically operable instrument, a floating valve arranged to open towards and to control the same, a pneumatic relay governing said valve and including a diaphragm chamber, whereby the amount of pressure in said chamber will determine the lift of and the throttling eiTect exerted by said floating valve, said chamber being provided with an admission port and a discharge port, an armature plate normally closing said admission port, a keycontrolled electro-magnet adapted to lift said plate, whereby said admission port will be opened.

MAX MAAG. 

